1. Field of the Invention
This invention relates to a programmable controller for performing sequential control of controlled machines.
2. Description of the Related Art
A programmable controller is used for sequentially controlling controlled machines. Input machines (e.g., switches and sensors) and output machines (e.g., electromagnetic switches, relays, solenoids and motors) are connected to the programmable controller.
A user program for sequentially controlling the controlled machines and various pieces of data including device information are stored in a storage section of the programmable controller.
The device information is information indicating the input state from an input machine, the output state to an output machine, and the state of an internal relay (auxiliary relay), a timer, a counter, data memory, etc., set in a user program. The device is a name referring to a memory area provided for storing the device information. Particularly, the internal relay, the timer, the counter, the data memory, and the like are called internal devices.
The user program of such a programmable controller is prepared using an external unit such as a dedicated programming unit and is transferred to the programmable controller. Such an external unit of a dedicated programming unit, etc., can also be used to monitor the device information (device value) of the programmable controller.
On the other hand, the programmable controller is provided with an analog trimmer for changing the values of the internal devices of the internal relay, the timer, the counter, the data memory, etc., without changing the user program.
For example, as shown in FIG. 11, an analog trimmer 500 as a knob is turned in the arrow R direction, whereby numeric data 0-249 responsive to the turn angle of the knob can be entered. As shown in FIG. 12, the value of the numeric data entered through the analog trimmer 500 can be set in the specified internal device on the user program.
In FIG. 12, TWIN is an instruction for transferring the numeric data corresponding to the turn angle of the analog trimmer 500 to an internal register. STA is an instruction for transferring the value of the internal register to the specified internal device such as the internal relay, the timer, the counter, or the data memory.
The example in FIG. 12 indicates transfer of the numeric data corresponding to the turn angle of the analog trimmer of trimmer number 0 to the internal register and transfer of the value of the internal register to timer T000 as a setup value. Thus, the setup value of the timer T000 can be changed by turning the analog trimmer 500 without changing the user program contents.
However, to use the analog trimmer 500 of the related programmable controller, there is a possibility that a shock to the programmable controller or careless touching of the analog trimmer 500 will shift the turn angle of the analog trimmer 500, changing the entered numeric data value.
If the analog trimmer 500 is placed in the depth of the cabinet of the programmable controller, a tool such as a screwdriver becomes necessary. Further, with the analog trimmer 500, it is difficult to accurately keep track of the current value entered. The resolution of the analog trimmer 500 is unique to the trimmer and cannot be changed.
On the other hand, to change or reference the device value of the programmable controller, an external unit such as a dedicated programming unit becomes necessary. Thus, the device value cannot be easily referenced or changed.
It is an object of the invention to provide a programmable controller for enabling a device value to be set, changed and referenced both easily and accurately.
According to one aspect of the invention, there is provided a programmable controller for sequentially controlling a controlled machine in accordance with a program, the programmable controller comprising storage means having a storage area defined as a device, a key for entering data, setting and changing means for setting a device value in the storage area of the storage means or changing the device value set in the storage area based on the data entered by operating the key, and a display section for displaying the device value set in the storage area of the storage means.
In the programmable controller according to the invention, a device value is set in the storage area of the storage means or the device value set in the storage area of the storage means is changed based on the data entered by operating the key. The device value set in the storage area of the storage means is displayed on the display section.
Therefore, the device value can be set, changed and reference easily and accurately by performing simply key operation.
In the programmable controller according to another aspect of the invention, the setting and changing means sets a device value defined in the program in the storage area of the storage means or changes the device value defined in the program based on the data entered by operating the key.
In this case, the device value defined in the program is set or changed and displayed, so that it is not feared that any other device value may be set or changed carelessly.
In the programmable controller according to another aspect of the invention, the storage means has a plurality of storage areas provided in a one-to-one correspondence with a plurality of devices, the key is used to select any of the plurality of devices, the setting and changing means sets the value of the device selected by operating the key in the corresponding storage area of the storage means or changes the device value set in the corresponding storage area of the storage means based on the data entered by operating the key, and the display section displays the value of the device selected by operating the key from among the device values set in the plurality of storage areas of the storage means.
In this case, any of the devices is selected by operating the key and the value of the selected device can be set, changed or referenced.
As the programmable controller according to yet another aspect of the invention, the invention further includes key invalidation means for invalidating operation of the key.
In this case, key operation is invalidated by the key invalidation means, whereby the device value can be prevented from being changed undesirably.
As the programmable controller according to another aspect of the invention, there further includes upper limit value setting means for setting the data entered by operating the key as an upper limit value of a device value.
In this case, the upper limit value of a device is set as desired, whereby the resolution of the setting and changing means can be adjusted as desired.
As the programmable controller according to a further aspect of the invention, the key is used to execute a predetermined instruction, and the programmable controller further includes instruction execution means for executing the predetermined instruction as the key is operated.
In this case, a predetermined instruction can be executed by operating the key without using an external unit such as a dedicated programming unit.
The entire disclosure of each and every foreign patent application from which the benefit of foreign priority has been claimed in the present application is incorporated herein by reference, as if fully set forth.